Delivery of antiplaque agents from dentifrices, gels, and mouthwashes

CPC-containing oral rinses inactivate SARS-CoV-2 variants and are active in the presence of human saliva

Introduction. The importance of human saliva in aerosol-based transmission of SARS-CoV-2 is now widely recognized. However, little is known about the efficacy of virucidal mouthwash formulations against emergent SARS-CoV-2 variants of concern and in the presence of saliva.

Hypothesis. Mouthwashes containing virucidal actives will have similar inactivation effects against multiple SARS-CoV-2 variants of concern and will retain efficacy in the presence of human saliva.

Aim. To examine in vitro efficacy of mouthwash formulations to inactivate SARS-CoV-2 variants.

Methodology. Inactivation of SARS-CoV-2 variants by mouthwash formulations in the presence or absence of human saliva was assayed using ASTM International Standard E1052-20 methodology.

Results. Appropriately formulated mouthwashes containing 0.07 % cetylpyridinium chloride but not 0.2 % chlorhexidine completely inactivated SARS-CoV-2 (USA-WA1/2020, Alpha, Beta, Gamma, Delta) up to the limit of detection in suspension assays. Tests using USA-WA1/2020 indicates that efficacy is maintained in the presence of human saliva.

Conclusions. Together these data suggest cetylpyridinium chloride-based mouthwashes are effective at inactivating SARS-CoV-2 variants. This indicates potential to reduce viral load in the oral cavity and mitigate transmission via salivary aerosols.

Biomineralization of Dental Tissues Treated with Silver Diamine Fluoride

Silver diamine fluoride (SDF) is a dental biomaterial used to arrest dental caries. To better understand SDF's mechanism of action, we examined the localization of silver within the tissues of SDF-treated teeth. Carious primary teeth fixed within 2 min of SDF application (SDF-minutes, n = 3), at 3 wk after SDF application in vivo (SDF-weeks, n = 4), and at 2 y after multiple SDF applications in vivo (SDF-multiple, n = 1) were investigated in this study. Carious primary teeth without SDF application (no-SDF, n = 3) served as controls. Mineral density and structural analyses were performed via micro-X-ray computed tomography and scanning electron microscopy. Elemental analyses were performed through X-ray fluorescence microprobe and energy-dispersive X-ray spectroscopic techniques. SDF-treated teeth revealed higher X-ray-attenuated surface and subsurface regions within carious lesions, and similar regions were not present in no-SDF teeth. Regions of higher mineral density correlated with regions of silver abundance in SDF-treated teeth. The SDF penetration depth was approximated to 0.5 ± 0.02 mm and 0.6 ± 0.05 mm (mean ± SD) for SDF-minutes and SDF-weeks specimens, respectively. A higher percentage of dentin tubular occlusion by silver or calcium phosphate particles was observed in primary teeth treated with SDF-weeks as compared with SDF-minutes. Elemental analysis also revealed zinc abundance in carious lesions and around the pulp chamber. SDF-weeks teeth had significantly increased tertiary dentin than SDF-minutes and no-SDF teeth. These results suggest that SDF treatment on primary teeth affected by caries promotes pathologic biomineralization by altering their physicochemical properties, occluding dentin tubules, and increasing tertiary dentin volume. These seemingly serendipitous effects collectively contribute to the cariostatic activity of SDF.

Dysregulation of metallothionein and zinc aggravates periodontal diseases

BACKGROUND

Periodontitis (PD) is a multifaceted inflammatory disease connected to bacterial infection that results in the destruction of tooth supporting structures and eventually tooth loss. Given their involvement in infection and inflammation, both metallothionein (MT) and zinc (Zn) might play vital roles in the development and progression of PD. More specifically, both MT and Zn are heavily involved in regulating immune functions, controlling bacterial infection, balancing inflammatory responses, and reducing oxidative stress, all of which are associated with the pathogenesis of PD.

OBJECTIVE

This review paper will explore the physiological functions of MT and Zn and hypothesise how dysregulation could negatively affect periodontal health, leading to PD.

FINDINGS

Bacterial lipopolysaccharide (LPS) derived from periodontal pathogens, namely P. gingivalis initiates the acute phase response, thus upregulating the expression of MT which leads to the subsequent deficiency of Zn, a hallmark of periodontal disease. This deficiency leads to ineffective NETosis, increases the permeability of the gingival epithelium, and disrupts the humoral immune response, collectively contributing to PD. In addition, the presence of LPS in Zn deficient conditions favours M1 macrophage polarisation and maturation of dendritic cells, and also inhibits the anti-inflammatory activity of regulatory T cells. Collectively, these observations could theoretically give rise to the chronic inflammation seen in PD.

CONCLUSION

A disrupted MT and Zn homeostasis is expected to exert an adverse impact on periodontal health and contribute to the development and progression of PD.

Chemical plaque control - A brief review

Dental plaque is a complex microbial population of bacterial and salivary polymers present on the tooth surface. It is understood that human diseases must be avoided and a high social concern for the population as a whole. The argument for the implementation of successful prevention measures is strong for life-threatening diseases or those with serious morbidity. However, regardless of seriousness, the case for avoiding any disease may be based on the belief that it is easier to be healthy than dead or sick. Thus plaque prevention is an efficient way to both treat and avoid periodontal diseases, it is an important component of gingival and periodontal diseases' primary management.

BSP implementation of European S3 - level evidence-based treatment guidelines for stage I-III periodontitis in UK clinical practice

OBJECTIVES

To adapt the supranational European Federation for Periodontology (EFP) S3-Level Clinical Practice Guideline for treatment of periodontitis (stage I-III) to a UK healthcare environment, taking into account the views of a broad range of stakeholders, and patients.

SOURCES

This UK version is based on the supranational EFP guideline (Sanz et al., 2020) published in the Journal of Clinical Periodontology. The source guideline was developed using the S3-level methodology, which combined the assessment of formal evidence from 15 systematic reviews with a moderated consensus process of a representative group of stakeholders, and accounts for health equality, environmental factors and clinical effectiveness. It encompasses 62 clinical recommendations for the treatment of stage I-III periodontitis, based on a step-wise process mapped to the 2017 classification system.

METHODOLOGY

The UK version was developed from the source guideline using a formal process called the GRADE ADOLOPMENT framework. This framework allows for the adoption (unmodified acceptance), adaptation (acceptance with modifications) and the de novo development of clinical recommendations. Using this framework and following the S3-process, the underlying systematic reviews were updated and a representative guideline group of 75 delegates from 17 stakeholder organisations was assembled into three working groups. Following the formal S3-process, all clinical recommendations were formally assessed for their applicability to the UK and adoloped accordingly.

RESULTS AND CONCLUSION

Using the ADOLOPMENT protocol, a UK version of the EFP S3-level clinical practice guideline was developed. This guideline delivers evidence- and consensus-based clinical recommendations of direct relevance to the dental community in the UK.

CLINICAL SIGNIFICANCE

The aim of S3-level guidelines is to combine the evaluation of formal evidence, grading and synthesis with the clinical expertise of a broad range of stakeholders to form clinical recommendations. Herein, the first major international S3-level guideline in dentistry, the EFP guideline, was implemented for direct clinical applicability in the UK healthcare system.

Treatment of stage I-III periodontitis-The EFP S3 level clinical practice guideline

BACKGROUND

The recently introduced 2017 World Workshop on the classification of periodontitis, incorporating stages and grades of disease, aims to link disease classification with approaches to prevention and treatment, as it describes not only disease severity and extent but also the degree of complexity and an individual's risk. There is, therefore, a need for evidence-based clinical guidelines providing recommendations to treat periodontitis.

AIM

The objective of the current project was to develop a S3 Level Clinical Practice Guideline (CPG) for the treatment of Stage I-III periodontitis.

MATERIAL AND METHODS

This S3 CPG was developed under the auspices of the European Federation of Periodontology (EFP), following the methodological guidance of the Association of Scientific Medical Societies in Germany and the Grading of Recommendations Assessment, Development and Evaluation (GRADE). The rigorous and transparent process included synthesis of relevant research in 15 specifically commissioned systematic reviews, evaluation of the quality and strength of evidence, the formulation of specific recommendations and consensus, on those recommendations, by leading experts and a broad base of stakeholders.

RESULTS

The S3 CPG approaches the treatment of periodontitis (stages I, II and III) using a pre-established stepwise approach to therapy that, depending on the disease stage, should be incremental, each including different interventions. Consensus was achieved on recommendations covering different interventions, aimed at (a) behavioural changes, supragingival biofilm, gingival inflammation and risk factor control; (b) supra- and sub-gingival instrumentation, with and without adjunctive therapies; (c) different types of periodontal surgical interventions; and (d) the necessary supportive periodontal care to extend benefits over time.

CONCLUSION

This S3 guideline informs clinical practice, health systems, policymakers and, indirectly, the public on the available and most effective modalities to treat periodontitis and to maintain a healthy dentition for a lifetime, according to the available evidence at the time of publication.

Clinical Trials with Herbal Products for the Prevention of Dental Caries and Their Quality: A Scoping Study

It is currently recognized that an injudicious strategy about caries in the last decades has been not only focusing of research mostly in children, but also the narrow focusing on fluoride, because despite sufficient availability of fluoride in water and oral healthcare products, caries levels escalate steadily as people get older and caries remain a main public health issue to be settled. In the last two decades the scientific community intensified efforts of exploring other products for caries prevention, herbal products being one of these approaches. Preliminary evidence indicated that clinical trials for caries prevention with herbal products are heterogeneous in design, quality and products evaluated, we therefore performed a scoping review intended to explore the main characteristics of such clinical trials. From an initial collection of 1986 unique papers from different literature databases, 56 articles satisfied the inclusion and exclusion criteria. The species investigated, dosage forms, study designs, duration of intervention, controls, endpoints, quality of reporting, and risk of bias are discussed. Of the trials reviewed here, 85.71% reported positive results but given the methodological flaws and biases affecting them, it is difficult to conclude on the efficacy of those products based on the studies published thus far.

A novel lidocaine hydrochloride mucoadhesive films for periodontal diseases

Periodontal diseases are inflammatory disorders caused primarily by dental plaque microorganisms that even may need surgery to remove damaged tissue. Adhesive biocompatible films may be an adequate form in order to improve drug retention or prevent microbial infections by covering the surgical site. In recent years, much attention has been focused on biocompatible inexpensive polymers, for biomedical and pharmaceutical potential applications. The objective of this research is the development of a film for mucosal application containing lidocaine hydrochloride (5%, w/w) as anesthetic drug. Lidocaine films were prepared with three biopolymers: hydroxypropylmethylcellulose (HPMC), chitosan (CH), or xanthan gum (XG). Their thickness and uniformity content were characterized. Rheological behavior of the hydrated films was studied using flow curves, creep and recovery tests and dynamic oscillatory measurements with a rheometer. The mucoadhesive assays were carried out with cheeks of Wistar rat using a universal tensile tester to know their adhesiveness. Finally, lidocaine delivery through the films was investigated in Franz cells. All films (n = 3 for each polymer) showed flexibility, a drug content of 0.015 ± 0.001 g/cm² and a thickness of 0.25 ± 0.01 mm. The results of the maximum detachment force in tensile tests and work adhesion indicated that XG is the polymer that showed greater power of mucoadhesion (p < 0.05). These properties show a good correlation with the rheological characteristics. In all cases, the lidocaine amount released at 30 min is around 4 mg/cm². This amount could be considered sufficient to guarantee the anesthetic effect.

Effect of Freeze Dried Powdered Probiotics on Gingival Status and Plaque Inhibition: A Randomized, Double-blind, Parallel Study

Objective:

The study aimed to evaluate the effectiveness of freeze dried powdered probiotics on gingival status and plaque inhibition among 12–15-year-old schoolchildren.

Materials and Methods:

This randomized controlled trial was conducted among 12–15-year-old schoolchildren in Jaipur. Commercially available freeze dried probiotics containing Lactobacillus acidophilus, Bifidobacterium longum, Bifidobacterium bifidum and Bifidobacterium lactis (Prowel, Alkem Laboratories), lactic acid bacillus only (Sporolac, Sangyo), and a placebo powder calcium carbonate 250 g (Calcium Sandoz, Novartis) were assigned to two intervention groups and a placebo group each comprising 11 schoolchildren. All subjects were instructed to mix the powder in 30 ml of water and swish once daily for 3 min, for 3 weeks. Periodontal clinical parameters were assessed by examining the subjects for Turesky-Gilmore-Glickman plaque index (PI) (Modification of Quigley-Hein PI) and gingival index at baseline, 7^th day, 14^th day, and 21^st day.

Results:

For both the probiotic groups, a statistically significant reduction (P < 0.05) in gingival status and plaque inhibition was recorded up to 2^nd week of probiotic ingestion. However, no significant difference was observed in the placebo group.

Conclusion:

The use of probiotic mouth rinses improves the oral health in children by significantly reducing the plaque and gingival scores. Further studies are warranted to prove or refute the long-term effects, means of administering probiotics and the dosages needed to achieve different preventive or therapeutic purposes.

UV-cured thiol–ene eugenol/ZnO composite materials with antibacterial properties

ZnO nanoparticles, i.e. efficient antimicrobial inorganic compounds, are combined to eugenol-based networks to design by “click chemistry” new promising eugenol/ZnO composite with enhanced antibacterial properties for biomedical applications.

Cytotoxic effects of octenidine mouth rinse on human fibroblasts and epithelial cells - an in vitro study

OBJECTIVES

This study compared the cytotoxicity of a new octenidine mouth rinse (MR) against gingival fibroblasts and epithelial cells with different established MRs.

METHODS

The following MRs were used: Octenidol (OCT), Chlorhexidine 0.2% (CHX), Listerine (LIS), Meridol (MER), Betaisodona (BET); and control (medium only). Human primary gingiva fibroblasts and human primary nasal epithelial cells were cultivated in cell-specific media (2 × 10(5) cells/ml) and treated with MR for 1, 5, and 15 min. Each test was performed 12 times. Metabolism activity was measured using a cytotoxicity assay. A cellometer analyzed cell viability, cell number, and cell diameter. The data were analyzed by two-way analysis of variance with subsequent Dunnett's test and additional t-tests.

RESULTS

The cytotoxic effects of all MRs on fibroblasts and epithelial cells compared to the control depended on the contact time (p < 0.001). OCT and BET showed less influence on cell metabolism in fibroblasts than other MRs. OCT also demonstrated comparable but not significant results in epithelial cells (p > 0.005). Cell numbers of both cell types at all contact times revealed that OCT showed a less negative effect (p > 0.005), especially for epithelial cells compared to CHX after 15 min (p < 0.005). OCT and BET showed the best results for viability in fibroblasts (p > 0.005), but MER showed less influence than OCT in epithelial cells (p < 0.005).

CONCLUSIONS

OCT is a potential alternative to CHX regarding cytotoxicity because of its lower cell-toxic effect against fibroblasts and epithelial cells.

Antibacterial and antiplaque efficacy of a commercially available octenidine-containing mouthrinse

OBJECTIVES

The purpose of this clinical study was to determine the antibacterial and antiplaque efficacy of a recently introduced octenidine-containing mouthrinse (Octenidol®) in comparison with established antiseptic mouthrinses.

MATERIALS AND METHODS

In a 4-day plaque-regrowth study employing a four-replicate cross-over design, a 0.1 % octenidine mouthrinse (Octenidol®/OCT-MR) was compared with a 0.12 % chlorhexidine mouthrinse (Paroex®/CHX-MR), an essential oil mouthrinse (Listerine®/EO-MR), and a placebo mouthrinse/P-MR. Plaque regrowth was assessed with a modified Quigley-Hein plaque index. The antibacterial effect was assessed by taking bacterial counts from the tooth surface and oral mucosa after professional tooth cleaning and after first rinsing with the allocated mouthrinse on days 1 and 5. Sixteen volunteers suspended tooth cleaning and rinsed twice daily with the allocated mouthrinse for 4 days.

RESULTS

All tested antiseptic mouthrinses were significantly more effective than the placebo mouthrinse in inhibiting plaque, but no significant differences were observed between OCT-MR and CHX-MR, OCT-MR and EO-MR, and CHX-MR and EO-MR. After 4 days, comparable bacterial count levels were found on both the tooth surface and mucosa applying OCT-MR and CHX-MR, which were significantly lower than that of EO-MR and P-MR.

CONCLUSION

Octenidol® and Paroex® showed comparable antibacterial and antiplaque efficacy in the human oral cavity.

CLINICAL RELEVANCE

The recently introduced octenidine-containing mouthrinse Octenidol® may become a suitable alternative to 0.12 % chlorhexidine-containing mouthrinses such as Paroex®.

Inhibitory Effects of Zinc Ions on Enamel Demineralisation Kinetics in vitro

Metal ions including zinc have the ability to influence enamel demineralisation. However, there is a paucity of data regarding reductions in demineralisation effected by zinc ions (Zn2+) in the literature. Therefore the aim was to measure the effects of zinc ion concentration ([Zn2+]) on the real-time in vitro demineralisation of enamel, during exposure to caries-simulating conditions, using scanning microradiography (SMR). Human enamel blocks were fixed in SMR environmental cells, through which acidic solutions (0.1 M acetic acid, pH 4.0) were circulated for periods of 50 h. SMR was used to quantitatively measure continuous mineral mass loss. Subsequently, the effects of sequentially increasing [Zn2+] (0.1-3,565 ppm) in the acidic solutions were measured on the rate of enamel demineralisation. This study demonstrated that Zn2+ even at low concentrations significantly reduces enamel demineralisation. There was a log-linear relationship between the mean percentage reduction in demineralisation and increasing [Zn2+] up to 3,565 ppm, i.e. the change in the overall percentage reduction in demineralisation was greater at lower concentrations than at higher concentrations, with 60% reduction at 36 ppm increasing to 90% at 3,565 ppm. In conclusion, SMR demonstrated the ability of Zn2+ to reduce the rate of enamel demineralisation under real-time in vitro acid conditions simulating dental caries. The results suggest that Zn2+ in the oral fluids could protect against enamel demineralisation during an acidic challenge. The log-linear relationship between [Zn2+] and demineralisation suggests that the reduction in enamel dissolution is limited by the saturation of surface sites on the enamel surface.

A comparative evaluation of the efficacy of probiotic and chlorhexidine mouthrinses on clinical inflammatory parameters of gingivitis: A randomized controlled clinical study

BACKGROUND

The aim of our clinical trial was to assess and compare the antiplaque and anti-inflammatory potential of a probiotic mouthwash with 0.2% chlorhexidine and saline.

MATERIALS AND METHODS

A randomized parallel group study was designed for a period of 4 weeks on 45 systemically healthy subjects between 20 and 30 years having chronic gingivitis. The study population was divided into three groups. Group A - 15 subjects were advised experimental (probiotic) mouthwash. Group B - 15 subjects were advised positive control (chlorhexidine) mouthwash and Group C - 15 subjects into a negative control group (normal saline). Oral prophylaxis was done for all groups at baseline. After the proper oral hygiene instructions, all the three groups were instructed to rinse their mouth with 10 ml of their respective mouthrinse, undiluted for 1 min twice daily, 30 min after brushing. Clinical parameters such as plaque index (PI), gingival index (GI), and oral hygiene index simplified (OHI-S) were assessed at baseline, 2 weeks and 4 weeks, respectively.

RESULTS

At day 28, the PI, GI, and OHI-S were significantly reduced by all treatment modalities ranking probiotic and chlorhexidine is greater than saline.

CONCLUSION

The probiotic mouthrinses tested was effectively used as an adjunct to mechanical plaque control in the prevention of plaque and gingivitis. Thus, the probiotic mouthrinse has a great therapeutic potential.

Can Chemical Mouthwash Agents Achieve Plaque/Gingivitis Control?

Also note that structured abstracts are not allowed per journal style: What is the effect of a mouthwash containing various active chemical ingredients on plaque control and managing gingivitis in adults based on evidence gathered from existing systematic reviews? The summarized evidence suggests that mouthwashes containing chlorhexidine(CHX) and essential oils (EO) had a large effect supported by a strong body of evidence. Also there was strong evidence for a moderate effect of cetylpyridinium chloride(CPC). Evidence suggests that a CHX mouthwash is the first choice, the most reliable alternative is EO. No difference between CHX and EO with respect to gingivitis was observed.

Formulation and preparation of stable cross-linked alginate-zinc nanoparticles in the presence of a monovalent salt

Polysaccharide-based nanoparticles can be formed, under the right conditions, when a counterion is added to a dilute polysaccharide solution. In this study, the possibility of preparing stable alginate nanoparticles cross-linked with zinc was investigated. The effects of the ionic strength of the solvent and the concentration of zinc were studied. The nanoparticles were characterized by dynamic light scattering, zeta potential and pH measurements. The results showed that an increase in the ionic strength of the solvent provided nanoparticles with considerably narrower size distributions compared to pure water, and a small size. The zinc content was shown to be an important factor for the formation of the nanoparticles. In fact, a critical zinc concentration was needed to obtain nanoparticles, and below this concentration particles were not formed. A stepwise increase in the amount of zinc revealed the process of formation of the nanoparticles. The stages of the nanoparticle formation process were identified, and differences according to the ionic strength of the solvent were also reported. Furthermore, the stability test of the most promising formulation showed a stability of over ten weeks.

The effect of various oral hygiene products on the microbial flora in patients undergoing orthodontic treatment

Context

Orthodontic devices lead to significantly greater plaque accumulation and gingival inflammation resulting in a change of gingival flora from cocci and rods to motile organisms like spirochetes.

Aims

The aim was to study the effect of various oral hygiene products on the microbial flora in patients undergoing orthodontic treatment.

Materials and Methods

The microbial composition of 40 patients, divided into four groups of 10 patients each, was evaluated. Group I patients were prescribed nonfluoridated dentifrice which act as the control group, Group II patients were given fluoridated dentifrice while in Group III and Group IV fluoridated mouth rinse and cetylpyridinium chloride mouth rinse, respectively, along with nonfluoridated toothpaste was prescribed. The plaque sample was collected at the start of orthodontic treatment, after 30 days, 60 days and 90 days for all the patients. The microscopic slides were prepared and observed under dark field microscopy at the magnification of ×1000 and microbes were classified as cocci, spirochetes, fusiforms, filaments, and rods.

Results

After applying analysis of variance and Tukey honest significant difference test, it was observed that after 30 days, only the proportion of filaments was found to be significantly higher in Group I. After 60 days, Group I had significantly lower proportion of cocci and a higher proportion of rods as compared to other groups. After 90 days, Group I had significantly higher count of rods, filaments, fusiforms, and spirochetes as compared to Groups III and IV.

Conclusion

Less amount of the microbial shift to the pathogenic organisms was seen in the patients in whom mouthwashes along with tooth brushing were prescribed.

Antibacterial properties of metal and metalloid ions in chronic periodontitis and peri-implantitis therapy

Periodontal diseases like periodontitis and peri-implantitis have been linked with Gram-negative anaerobes. The incorporation of various chemotherapeutic agents, including metal ions, into several materials and devices has been extensively studied against periodontal bacteria, and materials doped with metal ions have been proposed for the treatment of periodontal and peri-implant diseases. The aim of this review is to discuss the effectiveness of materials doped with metal and metalloid ions already used in the treatment of periodontal diseases, as well as the potential use of alternative materials that are currently available for other applications but have been proved to be cytotoxic to the specific periodontal pathogens. The sources of this review included English articles using Google Scholar™, ScienceDirect, Scopus and PubMed. Search terms included the combinations of the descriptors "disease", "ionic species" and "bacterium". Articles that discuss the biocidal properties of materials doped with metal and metalloid ions against the specific periodontal bacteria were included. The articles were independently extracted by two authors using predefined data fields. The evaluation of resources was based on the quality of the content and the relevance to the topic, which was evaluated by the ionic species and the bacteria used in the study, while the final application was not considered as relevant. The present review summarizes the extensive previous and current research efforts concerning the use of metal ions in periodontal diseases therapy, while it points out the challenges and opportunities lying ahead.

In Vitro Antimicrobial Activity of an Experimental Dentifrice Based on Ricinus Communis

This study evaluated the antimicrobial activity of a Ricinus communis-based experimental dentifrice for denture hygiene against the following standard strains: Staphylococcus aureus, Escherichia coli, Streptococcus mutans, Enterococcus faecalis, Candida albicans and Candida glabrata. The minimum inhibitory concentration (MIC) assay was performed with R. communis in pure oil at 2.5%. Only E. coli was not inhibited by R. communis, but the MIC (0.0781%) was effective against the other microorganisms. From these results it was determined the R. communis concentrations for experimental dentifrices, 1, 2, 5 and 10%, which were evaluated by the test-well diffusion in agar. The commercial dentifrices Colgate, Trihydral and Corega Brite were tested for comparative purposes. The diameter of the zones of bacterial growth inhibition produced around the wells was measured (in mm) with a rule under reflected light. Data were analyzed statistically by analysis of variance and Tukey's post-hoc test (α=0.05). Neither the commercial nor the experimental dentifrices were effective against E. coli. The experimental dentifrices containing R. communis at 2, 5 and 10% presented action against S. mutans, S. aureaus and E. faecallis. The experimental dentifrices showed no antimicrobial activity against Candida spp. and E. coli in any of the tested concentrations. Trihydral was the most effective. Comparing the experimental dentifrices, the product with 10% R. communis produced the largest zones of bacterial growth inhibition and had similar antimicrobial activity to the commercial dentifrices, except against S. aureus.

Physical chemical effects of zinc on in vitro enamel demineralization

OBJECTIVES

Zinc salts are formulated into oral health products as antibacterial agents, yet their interaction with enamel is not clearly understood. The aim was to investigate the effect of zinc concentration [Zn(2+)] on the in vitro demineralization of enamel during exposure to caries-simulating conditions. Furthermore, the possible mechanism of zinc's action for reducing demineralization was determined.

METHODS

Enamel blocks and synthetic hydroxyapatite (HAp) were demineralized in a range of zinc-containing acidic solutions (0-3565ppm [Zn(2+)]) at pH 4.0 and 37°C. Inductively coupled-plasma optical emission spectroscopy (ICP-OES) was used to measure ion release into solution. Enamel blocks were analysed by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and HAp by X-ray diffraction (XRD) and neutron diffraction (ND).

RESULTS

ICP-OES analysis of the acidic solutions showed a decrease in [Ca(2+)] and [PO4(3-)] release with increasing [Zn(2+)]. FTIR revealed a α-hopeite (α-Zn3(PO4)2.4H2O)-like phase on the enamel surfaces at >107ppm [Zn(2+)]. XRD and ND analysis confirmed a zinc-phosphate phase present alongside the HAp.

CONCLUSIONS

This study confirms that zinc reduces enamel demineralization. Under the conditions studied, zinc acts predominantly on enamel surfaces at PO4(3-) sites in the HAp lattice to possibly form an α-hopeite-like phase.

CLINICAL SIGNIFICANCE

These results have a significant implication on the understanding of the fundamental chemistry of zinc in toothpastes and demonstrate its therapeutic potential in preventing tooth mineral loss.

Antibiotic susceptibility of Aggregatibacter actinomycetemcomitans JP2 in a biofilm

BACKGROUND

Localized aggressive periodontitis (LAgP) is an inflammatory disease associated with specific bacteria, particularly Aggregatibacter actinomycetemcomitans, which can result in early tooth loss. The bacteria grow as a biofilm known as subgingival plaque. Treatment includes mechanical debridement of the biofilm, often associated with empirical antibiotic treatment.

OBJECTIVE

The aims of this study were to test in vitro the sensitivity of A. actinomycetemcomitans JP2 during planktonic and biofilm growth to doxycycline and to the combination of metronidazole and amoxicillin, which are two antibiotic protocols commonly used in clinical practice.

DESIGN

Two in vitro biofilm models were used to test the effects of the antibiotics: a static 96-well plate assay was used to investigate the effect of these antibiotics on biofilm formation whilst a flow chamber model was used to examine the effect on established biofilms.

RESULTS

Of the antibiotics tested in this model system, doxycycline was most efficacious with a minimal inhibitory concentration (MIC) against planktonic cells of 0.21 mg/L and minimal biofilm inhibitory concentration (MBIC) of 2.10 mg/L. The most commonly prescribed antibiotic regimen, amoxicillin + metronidazole, was much less effective against both planktonic and biofilm cells with an MIC and MBIC of 12.0 mg/L and 20.2 mg/L, respectively. A single treatment of the clinically achievable concentration of 10 mg/L doxycycline to sparse A. actinomycetemcomitans biofilms in the flow chamber model resulted in significant decreases in biofilm thickness, biovolume, and cell viability. Dense A. actinomycetemcomitans biofilms were significantly more resistant to doxycycline treatment. Low concentrations of antibiotics enhanced biofilm formation.

CONCLUSION

A. actinomycetemcomitans JP2 homotypic biofilms were more susceptible in vitro to doxycycline than amoxicillin + metronidazole.

Antimicrobial effects of o-cymen-5-ol and zinc, alone & in combination in simple solutions and toothpaste formulations

OBJECTIVES

This study aimed to evaluate antimicrobial effects of an o-cymen-5-ol/zinc system.

METHODS

o-Cymen-5-ol and zinc gluconate minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined against Streptococcus mutans, Actinomyces viscosus, Porphyromonas gingivalis, Fusobacterium nucleatum and Candida albicans. Synergy was investigated by checkerboard MIC/MBC; inhibition of P. gingivalis protease activity and S. mutans glycolysis were investigated. Slurried toothpastes containing the system were assessed in kill time assays against S. mutans and E. coli.

RESULTS

o-Cymen-5-ol MIC was between 1.7 mM to 3.4 mM; MBC was 3.4 mM to 6.7 mM. Zinc gluconate MIC was 2.8 mM to 11 mM; MBC was between 11 mM and >44 mM. The two agents in solution showed synergy (FICI≤0.50) against P. gingivalis and F. nucleatum, with MIC of 0.42 mM/0.69 mM for o-cymen-5-ol/zinc gluconate, respectively. Zinc inhibited glycolysis and protease to a greater degree than o-cymen-5-ol; glycolysis inhibition by the two agents was additive. o-Cymen-5-ol/zinc chloride in toothpaste showed greater effects than placebo (120s log10 kill=7.35±0.40 and 4.02±0.40, respectively).

CONCLUSIONS

The zinc/o-cymen-5-ol system has direct antimicrobial effects and inhibits oral disease-related processes. Synergistic effects were seen against anaerobes. A system combining o-cymen-5-ol and zinc shows properties desirable for incorporation in toothpastes.

Zinc in the mouth, its interactions with dental enamel and possible effects on caries; a review of the literature

Zinc is an essential trace element. In the mouth, it is present naturally in plaque, saliva and enamel. Zinc is formulated into oral health products to control plaque, reduce malodour and inhibit calculus formation. It has good oral substantivity, and elevated concentrations can persist for many hours in plaque and saliva following delivery from mouthrinses and toothpastes. Although low concentrations of zinc can both reduce enamel demineralisation and modify remineralisation, during caries clinical trials, the addition of zinc to fluoride toothpastes has not affected their ability to reduce caries. Mechanistic studies may help explain this apparent contradiction. Zinc is readily desorbed from hydroxyapatite by calcium, which is plentiful in plaque and saliva. Where crystal-growth sites remain occupied by zinc despite this, they may simply be 'over-grown' by remineralisation initiated at unoccupied sites. Further, under certain conditions, low concentrations of zinc can enhance remineralisation of enamel lesions, by retarding lesion arrestment. Although this may help to explain the apparent lack of an overall zinc effect on caries, it seems unlikely that any negative effects would be countered exactly by positive effects. Further mechanistic studies, complementing well-designed in vitro and in situ caries studies, should lead to further understanding of the zinc-enamel interactions relevant to demineralisation and remineralisation.

The interactions of epigallocatechin-3-gallate with human whole saliva and parotid saliva

OBJECTIVE

The aim of the present study was to assess the null hypothesis that the astringency and loss of lubrication in the oral cavity are not related to the properties of the epigallocatechin-3-gallate (EGCG) adlayer, the affinity and the entropy-drive of EGCG binding to saliva.

METHODS

The mass, thickness, and viscoelasticity of the EGCG adlayer and the temperature dependence of EGCG adsorption onto saliva surfaces were determined by quartz crystal microbalance with dissipation (QCM-D). The affinities of EGCG to human whole saliva (WS) and to parotid saliva (PS) were carried out by QCM-D monitoring and fluorescence quenching.

RESULTS

The stiffer and more compact EGCG adlayers were formed on saliva surfaces at various concentrations of EGCG. The affinity for EGCG binding to WS was higher than that to PS. The precipitation of EGCG/saliva was temperature-dependent. The driving force of EGCG binding to saliva is dominated by the hydrogen bond, the hydrophobic reaction, and the entropy-drive, which were confirmed by the FTIR spectra and the measurement of temperature- dependence, respectively.

CONCLUSION

The viscoelasticity of the EGCG adlayer, the affinity of EGCG to saliva, and the priority of EGCG binding to hydrophobic proteins on the mucosa may account for the oral astringency and loss of lubrication.

Effect of mouthrinses on Aggregatibacter actinomycetemcomitans biofilms in a hydrodynamic model

The aim of the study was to evaluate the effects of Listerine, Meridol, and Perioaid on the viability and total number of bacteria in established biofilms using an in vitro model under hydrodynamic conditions. Biofilms of Aggregatibacter actinomycetemcomitans were placed in a modified Robbins device and rinsed twice daily during 4 days. Bacteria were quantified by culture and quantitative polymerase chain reaction. Visualization of the samples was performed by scanning electron and confocal laser scanning microscopy, combined with a fluorescent vital staining. All three mouthrinses caused a significant reduction in the number of cultivable A. actinomycetemcomitans in a biofilm. Perioaid was significantly the most powerful in killing the biofilm-protected bacteria and also in counteracting the development of thick dense microbial communities. The total amount of bacteria was not significantly affected by Listerine and Meridol.

In Vitro Fluoride Release and the Antibacterial Effect of Glass Ionomers Containing Chlorhexidine Gluconate

Modification of inherent fluoride-containing materials with chlorhexidine provides an antibacterial and remineralizing varnish with potential anti-cariogenic properties.

Effect of two antimicrobial agents on early in situ biofilm formation

OBJECTIVES

The aim of this observer-blind, controlled, three-cell cross-over study was to evaluate the influence of an amine fluoride/stannous fluoride (Meridol, 250 ppm; ASF) and a chlorhexidine mouthrinse (CHX; Chlorhexamed forte, 0.2%) compared with water on in situ biofilm growth.

MATERIAL AND METHODS

After a professional toothcleaning seven volunteers had to wear a special acrylic appliance, in which six specimens each were inserted to allow the build-up of intra-oral biofilms. The volunteers had to rinse twice daily for 1 min. with 10 ml of the allocated mouthrinse. After 48 h of wearing, the specimens with the adhering biofilms were removed from the splints and stained with two fluorescent dyes, which selectively stain vital bacteria green and dead bacteria red. Under the confocal laser scanning microscope biofilm thickness (BT) was evaluated. To examine bacterial vitality (BV%) the biofilms were scanned (1 microm sections) and digital images were made. An image analysis program was used to calculate the mean BV as well as the BV of the single sections. After a wash-out period of 14 days a new test cycle was started.

RESULTS

The use of CHX and ASF resulted in a BT of 8.4+/-4.4 mum and 15.7+/-9.9 compared with 76.7+/-29.4 mum using water. The mean vitality (in %) was reduced from 66.1+/-20.4 to 23.3+/-11.6 and 23.9+/-12.4 using CHX and ASF, respectively. Both active solutions reduced BT and BV significantly compared with water (p<0.001). Differences between the two active solutions were not significant (p>0.05).

CONCLUSION

Both mouthrinses showed antibacterial and plaque-reducing properties against the in situ biofilm. The study design enables the examination of an undisturbed oral biofilm and for the first time shows the influence of antibacterial components applied under clinical conditions regarding biofilm formation.

The oral environment: the challenge for antimicrobials in oral care products

For any antibacterial/ anti-plaque system from an oral care product to be effective, it must firstly be delivered and retained at relevant sites in the oral cavity and secondly, remain active within the chosen formulation to successfully target the biofilm cells within dental plaque. This must include inhibition of the growth and metabolism of relevant organisms associated with disease. This review will concentrate on understanding the environmental conditions in which such oral care products must work and summarise the activity within the oral cavity of the main antibacterial and anti-plaque agents in common oral care products, namely chlorhexidine, essential oils, metal salts and Triclosan. Routes to further enhance the activity of these products, together with the use of relatively novel formats such as confectionery products to provide added consumer oral health benefits will be considered.

Plaque antibacterial levels following controlled food intake and use of a toothpaste containing 2% zinc citrate and 0.3% Triclosan

OBJECTIVES

To measure the levels of zinc and Triclosan present in plaque 12 hours post-brushing and following two weeks home use of a toothpaste formulation containing 2% zinc citrate and 0.3% Triclosan. To measure the levels of zinc and Triclosan in plaque following two weeks home use of the test toothpaste formulation together with a further morning's brushing and a day of controlled food intake.

METHODS

A total of 104 subjects completed the study. Plaque samples were taken before use of the test toothpaste and again after a specified regime of product use and food intake. The samples were analysed for zinc or Triclosan.

RESULTS

Levels of zinc and Triclosan in plaque 12 hours after last brushing and following a 2-week home usage of product, were 149.1 microg/g and 8.6 microg/g respectively. Following a morning brushing and a day of controlled food intake zinc and Triclosan levels were 94.7 microg/g and 4.1 microg/g respectively. These levels of agents were found to reduce pH drop in vitro.

CONCLUSIONS

Regular use of a toothpaste containing 2% zinc citrate and 0.3% Triclosan can lead to a build-up of antibacterial agents in plaque that continue to work even after controlled food intake.

The effect of a toothpaste containing 2% zinc citrate/0.3% Triclosan on the glycolysis of plaque bacteria ex vivo after food intake

OBJECTIVE

To develop an ex vivo plaque pH method to assess the efficacy of a new zinc citrate/Triclosan formulation.

METHODS

Study (1) focussed on method development. Study (2) examined the effect of a toothpaste containing 2% zinc citrate/0.3% Triclosan on the pH of plaque after product use and consumption of pizza. Study (3) investigated the effect of the same formulation and a fluoride toothpaste on the pH of plaque without an 'eating occasion'. The pH of plaque samples was measured over 10 minutes in the presence of glucose.

RESULTS

The test product significantly reduced the amount of acid produced 30 minutes (p = 0.0035) and 3 hours (p = 0.0018) after brushing (study (2)). In study (3) use of the test product significantly reduced the amount of acid produced 3 hours after brushing (p = 0.0023). No significant benefit was found for the fluoride toothpaste.

CONCLUSION

An ex vivo plaque pH method has been developed which can detect changes in acid produced following brushing with different toothpastes. A toothpaste containing 2% zinc citrate/0.3% Triclosan significantly reduced the total acid produced for at least 3 hours after product use. Moreover it has been demonstrated that this effect is detectable even after eating.

Antimicrobial effects of a novel Triclosan/zinc citrate dentifrice against mixed culture oral biofilms

AIM

To compare the antimicrobial efficacy in vitro of a new fluoride system containing 0.3% Triclosan and 2.0% zinc citrate with a standard fluoride toothpaste against bacteria commonly isolated from dental plaque.

METHOD

Mature biofilms of fixed depth containing ten oral bacterial species were developed in a model system and then exposed to the formulations both in situ and ex situ.

RESULTS

The standard fluoride toothpaste had limited activity against the Gram positive species following 1 and 5 minutes ex situ exposure (p = 0.004 and p = 0.02, respectively) but none against the Gram negative species; also, no overall effect following repeated pulsing in situ was observed. In contrast, viable counts of Gram positive and Gram negative species were markedly reduced following ex situ exposure for 1 and 5 minutes to the new formulation (Gram positive: p = 0.0007 and p = 0.04; Gram negative: p = 0.04 and p = 0.00001, respectively). Counts of Gram positive bacteria were reduced by 99.9% over a 4-day in situ pulsing period, while no Gram negative species were recoverable from the biofilm by day 4.

CONCLUSION

The new toothpaste formulation had a broad spectrum of antimicrobial activity against biofilm consortia containing bacteria associated with both dental caries and periodontal diseases.

Anti-plaque agents in the prevention of biofilm-associated oral diseases

The prevention of dental caries and periodontal diseases is targeted at the control of dental plaque. In this context, chemical agents could represent a valuable complement to mechanical plaque control. The active agents should prevent biofilm formation without affecting the biological equilibrium within the oral cavity. Depending on the goals of the preventive measures, various strategies may be considered. Anti-plaque agents with properties other than bactericidal or bacteriostatic activities may be used in primary prevention. In this approach, a modest antiplaque effect may be sufficient or even desirable, as it would decrease the side effects of the active agent. Antimicrobial agents are best indicated in secondary and tertiary prevention, as the objectives are to restore health and to prevent disease recurrence. The rational is to prevent or delay subgingival recolonization by pathogenic micro-organisms. The development of in vitro oral biofilm models certainly represents a major advance for studying and testing oral anti-plaque agents in recent years. The results of these studies have shown that chlorhexidine, hexetidine, delmopinol, amine fluoride/stannous fluoride, triclosan, phenolic compounds, among others, may inhibit biofilm development and maturation as well as affect bacterial metabolism.

Influence of dentifrices and dietary components in saliva on wettability of pellicle-coated enamel in vitro and in vivo

In vitro salivary pellicles were found to be less hydrophobic by water contact angles than clinically formed pellicles. In this study, water contact angles were measured on enamel coated with pellicles adsorbed from reconstituted human whole saliva (RHWS) and after exposure to dentifrices or dietary components. In addition, adhesion of Streptococcus oralis J22 to pellicles formed from RHWS with minor amounts of milk added and after exposure to dentifrices was studied. Exposure of RHWS-pellicles to milk or salad oil yielded an increase in the hydrophobicity of in vitro pellicles to values observed in vivo, but a decrease was seen after exposure to a sugar solution. Pellicles formed from saliva with 0.4% milk added attracted less S. oralis cells than pellicles formed in the absence of milk components. Exposure of pellicles formed from saliva with milk added to various dentifrices had a variable effect on bacterial adhesion: markedly lower numbers of adhering S. oralis were found for a dentifrice with NaF, but exposure to dentifrices containing SnF2 or hexametaphosphate showed slightly increased adhesion. In summary, dietary components have influence on the hydrophobicity of enamel pellicles, while combinations of dietary components and dentifrices certainly influence the adhesiveness of the pellicles. The effects of dietary components on pellicle conditioning film should be taken into consideration in research on the development of ingredients to control intraoral surface chemistry and microbiology, as well as in the development of oral products.

Antiplaque biocides and bacterial resistance: a review

Modern dentistry emphasizes the importance of dental plaque control to improve oral health. The use of oral care formulations with antiplaque biocides plays a crucial role in patient-directed approaches for plaque control. The antiplaque efficacies of these formulations have been extensively studied in many long-term clinical studies designed in accordance with well-accepted guidelines. The results from these studies conclusively demonstrate that long-term use of oral care formulations with well-known antiplaque biocides such as chlorhexidine and triclosan reduce supragingival plaque and gingivitis. This review summarizes microbiological results from clinical studies conducted with oral care formulations containing antiplaque biocides. Results from a number of long-term clinical studies conducted under real-life use conditions indicate no adverse alterations in the bacteria found in dental plaque or emergent microbial resistance. Additionally, microbial sampling of dental plaque subsequent to extended use of antiplaque biocides reveals no increase in resistant microflora. Large numbers of common oral bacteria isolated from patients using chlorhexidine indicate no increase in microbial resistance to chlorhexidine or to commonly used antibiotics. The effects of antiplaque biocides containing oral care formulations on dental plaque that exists naturally as a biofilm are examined. These formulations contain biocide, surfactants, polymers and other components that are effective against the biofilm. In summary, the results of studies on the real-life use of oral care formulations with antiplaque biocides show no emergence of resistant microflora or alterations of the oral microbiota, while such formulations have been found to provide the benefits of reducing plaque and gingivitis.

A study to assess the plaque inhibitory action of a newly formulated triclosan toothpaste

BACKGROUND/AIMS

Triclosan containing toothpastes have been noted for their potential to inhibit plaque and gingival inflammation. The aim of this study was to determine whether a toothpaste containing triclosan and an enhanced fluoride system would inhibit de novo plaque formation beyond that of a non-triclosan, conventional fluoride toothpaste.

METHODS

This study used a 4-day plaque regrowth model in which 24 volunteers used toothpaste rinses as the only form of oral hygiene. Following a prophylaxis and a single brushing with the toothpastes, 2x daily rinsing with toothpaste slurries was used over the following 96 h.

RESULTS

After 24 h, there was no difference in plaque area between the triclosan paste and its control paste. After 96 h, a reduction in plaque score of 5% was noted for the test toothpaste compared to the control paste which was statistically significant (p=0.028). For plaque area this reduction was increased to 16%, which was also significant (p=0.006).

CONCLUSIONS

These findings would appear to warrant further investigation into the potential value of the paste in inhibiting both plaque and gingivitis.

Effect of cyclodextrins and polymers on triclosan availability and substantivity in toothpastes in vivo

The aqueous solubility of triclosan is only about 10 microg/mL. This very low solubility can hamper its biological activity in the oral cavity, which could explain the mixed clinical results obtained from triclosan toothpaste trials. Triclosan availability in a silica-based toothpaste was improved through cyclodextrin solubilization. The triclosan in vivo availability was optimized through a series of phase-solubility studies and triclosan release studies. It was found that in toothpastes, natural beta-cyclodextrin (betaCD) was just as good a solubilizer as the more water-soluble betaCD derivatives. Furthermore, the amount of cyclodextrin could be reduced by as much as 60% through the addition of a small amount of carboxymethylcellulose (CMC), without affecting triclosan release from the toothpaste. Optimally, cyclodextrins resulted in an almost 3-fold enhancement of triclosan availability compared to an identical toothpaste containing no cyclodextrin. In vivo studies in humans showed that replacing triclosan with triclosan/betaCD in the toothpaste resulted in only moderate improvement in triclosan substantivity. However, replacing triclosan with triclosan/betaCD/CMC complex resulted in significant improvement in triclosan substantivity. Furthermore, the in vivo studies showed that replacing free triclosan with triclosan/betaCD/CMC complex resulted in an almost 3-fold increase in initial triclosan concentration in saliva after brushing and about 2-fold increase in duration of activity.

Composition and susceptibility to chlorhexidine of multispecies biofilms of oral bacteria

Using a constant-depth film fermentor, we have grown a six-membered biofilm community with a bacterial composition similar to that found in supragingival dental plaque. Cryosectioning revealed the distribution of bacteria throughout the biofilm. Exposure to 0.2% chlorhexidine for up to 5 min had little effect on biofilm viability.